1. Technical Field
The present disclosure relates to a system and method for performing electrosurgical procedures. More particularly, the present disclosure relates to a system and method for measuring current of an electrosurgical generator using the voltage across a DC blocking capacitor.
2. Background of Related Art
Electrosurgery involves application of radio frequency electrical current (e.g., electrosurgical energy) to a surgical site to cut, ablate, coagulate, or seal tissue. The two basic types of electrosurgery employed are monopolar and bipolar electrosurgery. Both of these types of electrosurgery use an active electrode and a return electrode. In bipolar electrosurgery, the surgical instrument includes an active electrode and a return electrode on the same instrument or in very close proximity to one another, usually causing current to flow through a small amount of tissue. In monopolar electrosurgery, the return electrode is located elsewhere on the patient's body and is typically not a part of the electrosurgical instrument itself. In monopolar electrosurgery, the return electrode is part of a device usually referred to as a return pad.
Ablation is a monopolar procedure which is particularly useful in the field of neurosurgery and cancer tumor hyperthermia, where one or more RF ablation needle electrodes (usually of elongated cylindrical geometry) are inserted into a living body. A typical form of such needle electrodes incorporates an insulated sheath from which an exposed (uninsulated) tip extends. When RF energy is provided between the return electrode and the inserted ablation electrode, RF current flows from the needle electrode through the body. Typically, the current density is very high near the tip of the needle electrode, which tends to heat and destroy surrounding tissue.
In bipolar electrosurgery, the return electrode is placed in close proximity to the active electrode such that an electrical circuit is formed between the two electrodes (e.g., electrosurgical forceps). In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes. When the electrodes are sufficiently separated from one another, the electrical circuit is open and thus inadvertent contact with body tissue with either of the separated electrodes does not cause current to flow.